blender-animation

The saved excerpt is a snapshot from review. The external source remains the complete and most current version.

---
name: blender-animation
description: >-
  Animate 3D objects and characters in Blender with Python. Use when the user
  wants to keyframe properties, create armatures and rigs, set up IK/FK chains,
  animate shape keys for facial animation, edit F-Curves, use the NLA editor to
  blend actions, add drivers for expression-based animation, or script any
  animation workflow in Blender.
license: Apache-2.0
compatibility: >-
  Requires Blender 3.0+ with Python bpy module. Run scripts via:
  blender --background --python script.py
metadata:
  author: terminal-skills
  version: "1.0.0"
  category: design
  tags: ["blender", "animation", "rigging", "keyframes", "armature"]
---

# Blender Animation

## Overview

Create and control animations in Blender using Python. Keyframe object and bone transforms, build armatures with IK/FK rigs, animate shape keys for facial motion, edit F-Curves for timing control, layer actions in the NLA editor, and wire up drivers for expression-based automation — all scriptable from the terminal.

## Instructions

### 1. Keyframe object properties

```python
import bpy

obj = bpy.data.objects["Cube"]
# Keyframe location at multiple frames
for loc, frame in [((0,0,0), 1), ((5,0,3), 30), ((5,4,0), 60)]:
    obj.location = loc
    obj.keyframe_insert(data_path="location", frame=frame)

# Also works for rotation_euler, scale, single-axis (index=2 for Z), custom props
obj.rotation_euler = (0, 0, 3.14159)
obj.keyframe_insert(data_path="rotation_euler", frame=60)
obj.scale = (2, 2, 2)
obj.keyframe_insert(data_path="scale", frame=60)
obj["intensity"] = 1.0  # custom property
obj.keyframe_insert(data_path='["intensity"]', frame=30)
bpy.context.scene.frame_start, bpy.context.scene.frame_end = 1, 60
```

### 2. Control F-Curve interpolation and modifiers

```python
import bpy

action = bpy.data.objects["Cube"].animation_data.action
for fcurve in action.fcurves:
    for kp in fcurve.keyframe_points:
        kp.interpolation = 'BEZIER'  # CONSTANT, LINEAR, BEZIER, SINE, EXPO, BOUNCE, ELASTIC
        kp.easing = 'EASE_IN_OUT'   # AUTO, EASE_IN, EASE_OUT, EASE_IN_OUT
    # Cycles modifier to loop the animation
    mod = fcurve.modifiers.new(type='CYCLES')
    mod.mode_before = 'REPEAT'       # NONE, REPEAT, REPEAT_OFFSET, MIRROR
    mod.mode_after = 'REPEAT'

# Add noise to a specific channel
z_curve = action.fcurves.find("location", index=2)  # Z location
if z_curve:
    noise = z_curve.modifiers.new(type='NOISE')
    noise.strength, noise.scale = 0.3, 5.0
```

### 3. Create armatures and bones

```python
import bpy

arm_data = bpy.data.armatures.new("Rig")
arm_obj = bpy.data.objects.new("Rig", arm_data)
bpy.context.collection.objects.link(arm_obj)
bpy.context.view_layer.objects.active = arm_obj
bpy.ops.object.mode_set(mode='EDIT')
# (name, head, tail, parent_name, connected)
bone_defs = [
    ("Spine",      (0,0,1.0),   (0,0,1.4),   None,       False),
    ("Chest",      (0,0,1.4),   (0,0,1.8),   "Spine",    False),
    ("UpperArm.L", (0.2,0,1.7), (0.5,0,1.4), "Chest",    False),
    ("Forearm.L",  (0.5,0,1.4), (0.8,0,1.1), "UpperArm.L", True),
    ("Thigh.L",    (0.1,0,1.0), (0.1,0,0.5), "Spine",    False),
    ("Shin.L",     (0.1,0,0.5), (0.1,0,0.05),"Thigh.L",  True),
]
for name, head, tail, parent, connected in bone_defs:
    b = arm_data.edit_bones.new(name)
    b.head, b.tail = head, tail
    if parent:
        b.parent = arm_data.edit_bones[parent]
        b.use_connect = connected

bpy.ops.object.mode_set(mode='OBJECT')
```

### 4. Set up constraints on bones

```python
import bpy

arm_obj = bpy.data.objects["Rig"]
bpy.context.view_layer.objects.active = arm_obj
bpy.ops.object.mode_set(mode='POSE')
# IK — use an empty as target, chain_count limits affected bones
ik = arm_obj.pose.bones["Forearm.L"].constraints.new('IK')
ik.target = bpy.data.objects["IK_Target"]
ik.pole_target = bpy.data.objects["IK_Pole"]
ik.chain_count = 2

# Copy Rotation — mirrors another object's rotation
cr = arm_obj.pose.bones["Chest"].